1. Field of the Invention
This invention relates to a hold-down device for securing a die or die support plate to the flat bed or rotary chase of a graphic arts press. In particular, the invention concerns a hold-down device adapted to be positioned in a respective cavity of a chase and that has a removable component that engages and reliably secures a graphic arts die or die support plate in predetermined disposition on the chase.
2. Description of the Prior Art
Hot foil stamping and embossing graphic arts presses have a flat or rotary chase provided with a plurality of cavities in predetermined relative relationship. These chases are adapted to support one or more of the hot foil and/or embossing dies. Various toggle devices have long been provided for securing the dies to a respective chase in predetermined relative disposition. Prior toggle devices have been constructed to be removably received in a chase cavity, are operable to be locked in position, and include some type of gripper for engaging an edge portion of the die. A multiplicity of the toggle devices have been used around the perimeter of each graphic arts die and that have some type of fastener engageable with a central portion of the die or a support for a die that is secured to the chase.
One type of conventional toggle fastener or hook has two end-to-end pieces that are telescopically received in a chase cavity and that have interengaging inclined surfaces. Mechanism forming a part of the toggle fastener is adapted to receive a tool such that, as a result of manipulation of the tool, the two pieces of the fastener are drawn toward one another, thereby expanding the device as the inclined surfaces shift relatively whereby the die is locked in the cavity. A die-engaging element of the toggle fastener, which projects outwardly from a respective cavity when a fastener is installed, contacts an edge or surface of a die plate mounted on the chase. By providing a plurality of the toggle fasteners around the perimeter of a die or die support plate, the graphic arts die or die plate can be fixedly mounted on either a flat bed or rotary graphic arts press chase.
Toggle fasteners heretofore available have been relatively expensive to manufacture and sell for premium prices. The fasteners were complicated, did not always accomplish their intended holding function, and were prone to breakage and damage. Several hundred of the fasteners were required for jobs in which a substantial number of dies were directly mounted on a single chase platen. It, therefore, was not only costly for press operators to purchase and then rely on these prior art devices for die makeready procedures, but equally as important, it was time consuming and expensive because of the substantial hours that were required for press operators to install the large number of toggle fasteners required for jobs involving a multiplicity of dies on each press chase, and to go through conventional makeready adjustments. Similarly, removal of the toggle fasteners for change out of dies involved significant expenditures of time. As development of toggle fasteners evolved, the fasteners became ever more complicated and therefore more expensive and difficult to install and remove.
Because the edge of a die plate, or a plate supporting a plurality of dies, frequently partially covered the closest chase openings when the die or die plate was positioned in a desired location on a flat bed or rotary chase, it was not possible to insert and utilize hold-down fasteners in the most advantageous locations. In addition, previously available toggle devices were often not usable in different sizes of cavities in flat bed or rotary press chases depending on the type of chase on a particular press.